Objectives: Renal cell carcinoma (RCC) is the most lethal urologic malignancy with increasing incidence worldwide. The conventional treatment strategies for advanced or recurrent RCC are not efficient and show considerable toxicities. Adoptive cell transfer (ACT) has become a promising treatment option for multiple cancers, particularly in combination with other therapeutic approaches. ACT often utilizes extensively in vitro expanded tumor-infiltrating lymphocytes (TILs). However, TILs are a very heterogeneous mix of cell populations and only those populations that have a cytotoxic and migratory potential are thought to deliver a therapeutic impact in ACT. The identification and localization of these therapeutically potent populations are therefore needed.
Methods and materials: A total number of 57 tissue samples from 19 RCC patients who underwent radical nephrectomy was analyzed. The tissue samples were obtained from the tumor, peritumoral tissue, and the adjacent healthy renal tissue. The tissues were sliced, enzymatically dissociated into single cell suspensions and the obtained cells further analyzed by flow cytometry for the expression of markers of lymphocyte cytotoxicity - TRAIL and FasL, and a surrogate marker of lymphocyte migratory activity - PECAM-1. The analyzed data were next correlated with the clinical and histopathological data.
Results: Non-clear cell RCC (non-ccRCC) tumors showed a significantly decreased tumor infiltration with TRAIL+FasL+ NK cells but elevated infiltration with FasL+PECAM-1+ T cells as compared with clear cell RCC (ccRCC) tumors. Further analyses revealed that the peritumoral tissue of ccRCC patients is a reservoir of TRAIL+FasL+, TRAIL+PECAM-1+, or FasL+PECAM-1+ NK and T cells.
Conclusions: The cytotoxic/migratory lymphocytes were identified in tumors of ccRCC patients. These lymphocytes became excluded from the tumor and accumulated in the patient's peritumoral tissue.
Keywords: FasL; PECAM-1; Renal cell carcinoma; TRAIL; Tumor-infiltrating lymphocytes; peritumoral.
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